The goal of this proposal is to develop a general method for the creation of chemically selective sensors for biomolecules. To this end, molecular recognition sites in self-assembled monolayers will be created by assembling monolayer constituents around template molecules via intermolecular interactions (ionic or hydrogen bonding). Subsequent removal of the template molecules by rinsing or cleavage will leave behind a recognition site for reabsorption of the template or very similar molecules. Infrared spectra of the adsorbed molecules and comparison of the adsorption isotherms of similar molecules will help elucidate the reasons behind recognition site specificities. Molecular sensors containing the recognition sites will then be developed using thickness shear mode resonators. To avoid interferences from nonspecific surface contamination, both frequency and attenuation of the resonator will be monitored during molecular adsorption because attenuation is less likely to be changed by nonspecific adsorption. By combining recognition site specificity with selective detection, discriminating sensors should be realized. Such sensors would prove useful in diagnostic (monitoring biological intermediates) as well as clinical applications (monitoring drug delivery).